Jeb Bush’s decision to attack old friend and new rival Marco Rubio is backfiring, pushing important supporters to criticize the campaign’s tactics and driving one of Florida’s top fundraisers to officially quit and signal a shift in allegiance to the senator.

“I think the world of Jeb Bush. He was a great governor of Florida and is a really good person, but the campaign has hijacked his message,” said Brian Ballard, a Tallahassee lobbyist who contributed more than $25,000 of his own money and has raised hundreds of thousands of dollars more for Bush’s campaign and the super PAC supporting him.

Story Continued Below

“The campaign has become negative, one that is about attacking and trying to bring down Marco Rubio. And that doesn’t sit well—not only with me, but with anyone who knows the two,” Ballard said. “Marco’s a friend of mine. I didn’t sign up for a campaign that was going to be negative and attack a bright star of the party’s future. It doesn’t make sense. I’m over it. And I’m done.”

Ballard said he decided to make his departure final and public after the Bush team called Rubio “the GOP Obama” and a “risky” bet due to his past personal financial struggles. Ballard said he stopped raising money for the campaign three months ago amid a dispute with the campaign.

One staffer familiar with Ballard’s conversations with the campaign was more blunt.

“While we appreciate Brian’s support of the governor, in August, we expressed to him serious concerns about his continued lack of discretion regarding campaign strategy — particularly in relation to his interaction with the national media,” said the staffer, noting that Ballard is a Donald Trump lobbyist. “He has not been actively engaged in this campaign or our team’s efforts for months, and his comments today are of little surprise to anyone. We wish him well.”

While Ballard’s decision and comments are the most striking, his sentiment of disappointment in the campaign was expressed to POLITICO in varying degrees by numerous Bush supporters — from members of Congress to those who have worked for the Bush campaign to donors who are unhappy with the direction of the election effort.

U.S. Rep. Pete Sessions, who counts George W. Bush as a Texas constituent and whose father, William, served as George H. W. Bush’s FBI director, said Jeb Bush put himself in a combative situation that’s an ill fit for him. “I don’t think it’s his strong suit,” said Sessions, still a Bush supporter. “I think it’s Donald Trump’s strong suit.”

And U.S. Rep. Carlos Curbelo — who, like Bush and Rubio, is a Miami-area Republican — said that while he still thinks Bush is the most-qualified to sit in the White House, attacking Rubio is neither effective, nor beneficial.

“The serious candidates in this race should focus on their policy proposals and résumés,” Curbelo said in an email to POLITICO. “Mud-slinging and efforts to disqualify one another will only serve to pave Hillary Clinton's path to the White House.”

Most of those who say they are disappointed with the attack-Rubio tactics blame the campaign’s senior leadership — not Bush personally.

One Republican who has worked for the Bush campaign said the staffers are taking Rubio’s bid for president personally, not professionally. Some have taken to calling Rubio “Judas,” a betrayer who should have deferred to the elder Republican, the source said, adding that the campaign’s upper echelon isn’t listening to the numerous voices in the conservative movement and the Republican Party who have become increasingly disillusioned with the negative tone.

“The campaign has been arrogant with donors, arrogant with staff, arrogant with Republicans and arrogant with the media,” the source said. “And now look at where we are: isolated.”

Worse yet for Bush, nearly all of the supporters who told POLITICO they are disappointed in his attack approach see Rubio as a viable alternative who would continue the tradition of conservative principles and policies that the former governor espoused when Rubio served simultaneously in the Florida Legislature. Already, they noted, Rubio is well ahead of Bush in national and state polls.

“For a substantial portion of the D.C. crowd — and I think this probably goes beyond D.C. — Marco is well liked,” said one major Bush donor and fundraiser from Washington. “I don’t know necessarily what is gained by picking fights with people.”

One reason the Bush campaign’s tactic has hit such a nerve is that, polls show, a high amount of Bush supporters favor Rubio as a second-choice candidate. And with Bush’s public support collapsing, many Republicans don’t want to see his campaign take Rubio down with it.

Ballard said he has not spoken to Rubio or his campaign about his disappointment in the Bush campaign or his decision to make his departure official. Ballard said this was the first campaign he publicly left since his first race when he worked for Gov. Bob Martinez in 1986. He was a national finance-committee member for the 2008 and 2012 presidential campaigns of John McCain and Mitt Romney, respectively, and led fundraising efforts for Gov. Charlie Crist and Gov. Rick Scott’s elections in 2010 and 2014, respectively.

Though he historically is the state’s top fundraiser, Ballard wasn’t the Bush campaign’s top money raiser. But he signed on early, along with other establishment Republicans, and raised money for the campaign.

If the Rubio campaign wanted, Ballard said, he would volunteer in any way they asked.

“The three smartest people I know are my three daughters. All three of them are for Marco Rubio, and have been despite my support for Jeb,” he said. “When they speak about Marco, they speak about someone who can get them involved in politics. That’s why Marco has so much potential. That’s clearly why so many in the Bush campaign feel like they have to strangle him in the crib. And that’s a damn shame.”

Bush spokesman Tim Miller referred POLITICO to statements Bush made this week on the campaign trail about Rubio, for whom the former governor said he has “respect.” Bush refrained from taking on Rubio directly — and last week, he said he hadn’t seen his campaign’s comments calling the senator a “GOP Obama” or a “risky” choice, but he did fault Rubio because he “didn’t change the culture of Washington.”

Certainly, many of Bush’s supporters are sticking with the onetime front-runner. U.S. Rep. Mario Diaz-Balart, for instance, said he didn’t think Bush was out of line in discussing Rubio’s missed Senate votes or in emphasizing the value of executive over legislative experience, though he cautioned against more personal attacks.

“I believe in Reagan’s 11th commandment. So that’s where I am,” Diaz-Balart said, referencing the former president’s maxim against speaking ill of fellow Republicans.

Others agree.

“Jeb has been and needs to continue to talk about the issues,” said Chicago investor Ron Gidwitz, a Bush donor who has contributed $100,000 to Bush’s super PAC, Right to Rise. “I see no reason why Jeb needs to attack anyone.”

Francis Rooney, a Bush donor who served as U.S. ambassador to the Holy See under President George W. Bush, said he “wouldn’t tell [Bush] what to do,” but stressed his belief that Bush should focus on an economic message, which is what attracted people to Bush in the first place. Rooney, whose investment company, Rooney Holdings, has contributed $2 million to Bush’s super PAC, also urged Jeb to distinguish himself from “attack dogs” who were on the debate stage.

Some Bush supporters didn’t mind Bush deciding to take on Rubio directly onstage over his missed Senate votes, but they winced at Rubio’s sharp retort that Bush was only doing it “because we’re running for the same position. Someone convinced you attacking me is going to help you.”

The idea of confronting Rubio was a good one, if not the execution.

“I think that was his judgment,” said Gidwitz. “Under the circumstances it was called for.”